Eulachon of the Pacific Northwest: a Life History
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Eulachon of the Pacific Northwest: A Life History Living Landscapes Program, Royal BC Museum Prepared January 11, 2006 by: Prepared for: Living Landscapes Program, Royal BC Museum 675 Belleville Street Victoria, BC V8W 9W2 Prepared by: Cambria Gordon Ltd. Suite 202, 4548 Lakelse Avenue Terrace, B.C. V8G 1P8 Tel: (250) 638.0498 Fax: (250) 638.0418 Living Landscapes Program Eulachon of the Northwest: A Cultural and Natural History TABLE OF CONTENTS 1 Introduction .................................................................................................. 1 2 Description ................................................................................................... 1 3 Habitat .......................................................................................................... 3 3.1 Estuary Habitats...................................................................................................... 3 3.2 Ocean Environments............................................................................................... 3 3.3 Fresh Water (River) Environments......................................................................... 3 4 Importance.................................................................................................... 5 4.1 First Nations............................................................................................................ 5 4.2 Wildlife ................................................................................................................... 6 5 Management ................................................................................................. 6 6 Conclusion.................................................................................................... 7 References....................................................................................................... 7 List of Figures Figure 1: Female spawning eulachon on left and male spawning eulachon on right. Note the large ventral fins on the male................................................................................ 1 Figure 2: Eulachon eggs along the riverbank of the Kemano River................................... 2 Figure 3: Eulachon Larvae.................................................................................................. 2 Figure 4: Skeena River looking west.................................................................................. 4 Figure 5: Eulachon spawning rivers on the west coast of North America.......................... 4 Figure 6: Haisla First Nation 2003 Eulachon Fishery on the Kemano River ..................... 5 Figure 7: Steller Sea Lion in Kemano River....................................................................... 6 ii Living Landscapes Program Eulachon of the Northwest: A Cultural and Natural History 1 Introduction Eulachon, or oolichan, as they are also known, is a small fish in the smelt family, Osmeridae. Their scientific name Thaleichthys pacificus comes from the Greek word Thaleia, which means rich, and ichthys, which means fish. Pacificus means that they live in the Pacific Ocean. They are anadromous (live in saltwater, but spawn in freshwater) and migrate into some of the major river systems along the west coast of North America to spawn in the early spring every year. Eulachon are important fish for many reasons. They are the first arrivals to the river after winter and are a staple food source for many First Nations people along the coast. Eulachon are prepared many ways including having the grease rendered for packing and consumption. Grease trails from the coast through the interior of British Columbia mark the importance of eulachon grease as a trade item between coastal and interior First Nations. 2 Description Eulachon are long, slender fish, reaching approximately 15-20cm in length and weighing 40-60 grams (Stoffels, 2004). The males are slightly larger than females. They are bright silver in colour and have no marks or spots on their bodies, fins or tails. The males are distinguishable during spawning season because of their larger body size and because their ventral fins are longer and wider than the female’s fins. Figure 1: Female spawning eulachon on left and male spawning eulachon on right. Note the large ventral fins on the male. Eulachon are believed to spawn when they are 3-4 years old. They travel up river beyond the saltwater to spawn. Most eggs are laid at night onto clean sand or small gravel. Eulachon are broadcast spawners and the females release up to 25,000 eggs in the flowing water, and the males release milt at the same time. As the eggs are fertilized they are covered in a sticky substance that helps them adhere to the sand and gravel substrate. 1 Living Landscapes Program Eulachon of the Northwest: A Cultural and Natural History Figure 2: Eulachon eggs along the riverbank of the Kemano River. The eggs incubate for 3-4 weeks, depending on the water temperature, before the larvae hatch. Eulachon larvae are 4-5mm in length and do not look very much like adult fish. They have large eyes and a visible yolk sac that supplies their food during the early stages of their lives. After hatching they are carried downstream to the estuary of their natal stream, and out into the ocean where they feed on zooplankton and grow. Figure 3: Eulachon Larvae As a schooling fish, eulachon travel together in the ocean. They have been found to live near the ocean bottom at depths of 20-150m (Hay and McCarter, 2000). Schools of eulachon support a variety of ages and the adult eulachon that reach sexual maturity in the late summer or early fall leave the schools of younger fish to swim to the rivers in preparation for spawning. It is believed that eulachon return to the estuary of their birth, but it is not known if they return to the same river from where they hatched. (Hay and McCarter, 2000). 2 Living Landscapes Program Eulachon of the Northwest: A Cultural and Natural History 3 Habitat 3.1 Estuary Habitats Larval eulachon use estuaries for their early life stage. Estuarine vegetation like sedge grasses, provide shelter from predators and opportunities to forage for food. Eulachon typically enter their juvenile stage of life (8 weeks to 12 months) in this estuarine environment. At this stage they resemble adult fish more than the larval appearance they had when they hatched. They also develop the schooling behaviour. The fish are approximately 3cm in length as they enter the juvenile stage of life. As they grow, they move into ocean environments. It is believed that eulachon leave the estuary for the ocean within the first year after hatching, but it is not confirmed how soon after hatching, or how long the fish stay in the estuary. After living in the ocean for 1 to 3 years, the eulachon come back to the estuaries in preparation for going up stream. While in the estuary their bodies adapt so they can survive in fresh water and get ready to spawn. 3.2 Ocean Environments Distribution in the ocean has been identified through studies of eulachon as by-catch for shrimp trawlers. This information is limited to locations where shrimp trawling has taken place. Eulachon have been caught along the coast throughout British Columbia, although research trawls caught very few fish off north eastern Vancouver Island and the outer coasts of the Queen Charlotte Islands. Higher catch levels were noted between the Queen Charlottes and the mainland and along the southwest coast of Vancouver Island. Another area of higher catch levels north of Vancouver Island, approximately 1/3 of the way to the Queen Charlotte Islands (Hay and McCarter, 2000). 3.3 Fresh Water (River) Environments Eulachon start and end their life cycles in fresh water. After spending 1 to 3 years at sea and having gone through their physical and biological adaptations to survive in fresh water, the eulachon begin their trip up river to spawning locations. At this time the fish resorb minerals from their scales and teeth in order to develop eggs and milt for spawning. There are 33 rivers in BC with known eulachon runs. Of these, 19 are considered irregular, having fish one year and no fish the next year. 3 Living Landscapes Program Eulachon of the Northwest: A Cultural and Natural History Figure 4: Skeena River looking west Some of the rivers with eulachon runs in BC include: Nass Kemano/Wahoo Kingome Kitimat Bella Coola Kiliniklini Skeena Kimsquit, Kwatna, Dean Fraser Kildala Chuckwall/ Kil bella Kitlope Kowesas Wannock There are also several rivers in south eastern Alaska, the Columbia River in Washington State, and three rivers in California that have supported eulachon runs (Figure 5). Figure 5: Eulachon spawning rivers on the west coast of North America. 4 Living Landscapes Program Eulachon of the Northwest: A Cultural and Natural History Eulachon eggs require fresh water to incubate. The fish tend to use rivers with spring freshets and go up the river beyond the extent of saltwater intrusion to spawn prior to the freshet. Timing of spawning varies with the stream and there is no trend that correlates timing of the spawn with the latitude of the river. All spawning takes place between late February and May in the rivers in British Columbia. 4 Importance Eulachon play a vital role to both wildlife and to First Nations people in BC. 4.1 First Nations As the first fish to return to the river after winter, eulachon were a valued source of fresh protein. They were also dried as a method of preservation. Another key role that eulachon played was as a trade item.